• 대한기계학회논문집A
• /
• 제30권11호
• /
• pp.1433-1438
• /
• 2006

A systematic approach to socket shape design of a concave piston assembly for a high pressure hydraulic pump of an excavator is presented in this paper. A design model is given and a methodology of socket shape design is proposed. An axisymmetric rigid-plastic finite element method is employed for predicting the approximate socket shape formed by a rotary forming process as well as for simulating the test process for separating the shoe from the piston assembly designed. It is verified that the predictions are in good agreement with the experiments. The approach is successfully applied to developing an optimal concave piston assembly.

• 유공압시스템학회논문집
• /
• 제2권4호
• /
• pp.14-22
• /
• 2005

The safety factor of hydraulic piston pumps & motors due to high pressurization, high speedization and low weight/volume realization to enhance the output density shows a tendency to decrease. Therefore more effective test methods are necessary to predict the exact life. The failure of hydraulic pumps & motors operating in high pressure and high speed mainly occurs in piston-shoe assemblies, and the major failure mode is wearout of the shoe surface. The sensitive parameters in the endurance life test are speed, pressure and temperature, and the failure production increases in proportion to the operating time. In this research, the authors propose the combined accelerated life test model using the analysis method of the combined accelerated life test results of piston-shoe assemblies by applying simultaneously high speed, high pressure and high temperature in accordance with variation of speed, pressure and temperature to reduce the life test time.

• 대한기계학회논문집A
• /
• 제36권11호
• /
• pp.1441-1446
• /
• 2012

유압피스톤모터는 정압베어링부분의 마찰손실과 용적손실, 기구적 운동부분의 마찰손실, 오일의 관로저항에 의한 압력저하, 압축성에 의한 체적손실 그리고 하우징 오일 처닝(churning) 손실 등이 있다. 이러한 손실 중에서 일정한 틈새의 유막(oil film, $8{\sim}15{\mu}m$)으로 고속 회전하는 피스톤 슈(piston shoe)와 슈 플레이트(shoe plate) 사이 정압베어링 부분의 마찰 및 용적손실이 유압모터의 전체효율을 좌우 한다. 본 연구에서는 최고압력 35MPa, 최고회전수 2500rpm, 배재용적 320cc/rev급 2속(2-speed) 초대형 굴삭기의 주행모터용 유압피스톤모터를 대상으로 정압베어링비가 유압모터의 전 효율에 미치는 영향을 실험적으로 분석하였다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2006년도 춘계학술대회 논문집
• /
• pp.353-358
• /
• 2006

A three-dimensional finite element approach to process analysis and design for joining the socket with the ball by a kind of the rotary forging processes is presented in this paper. The rigid-plastic finite element method is employed and its results are used to reduce the number of process design tryouts. The approach is applied to developing a concave piston assembly for a high pressure hydraulic pump. Experiments show that the developed piston assembly satisfies the quality requirement on geometrical tolerance.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.403-404
• /
• 2006

A finite-element based approach to socket shape design of a concave piston assembly for a high pressure hydraulic pump of an excavator is presented in this paper. The approach is applied to developing a concave piston assembly which fulfills its strength requirement and it is verified that the predictions are in good agreement with the experiments.

• 한국신뢰성학회:학술대회논문집
• /
• 한국신뢰성학회 2006년도 학술발표대회 논문집
• /
• pp.116-125
• /
• 2006

Piston assemblies, which are key components of hydraulic high pressure pumps & motors, are major failure products operating at high pressure and high speed, and the main failure mode is wearout of the shoe surface. To predict the actual life of piston assemblies. we require to find out the most sensitive parameters and establish related empirical formula. In this study, we analyzed the life of piston and shoe assemblies in accordance with variation of speed, pressure, and temperature to reduce the life test time, then analyzed the result of combined accelerated life test which is applied by high speed, speed pressure, and high temperature simultaneously, and finally developed combined accelerated life test model.

• 한국항공우주학회지
• /
• 제30권6호
• /
• pp.1-6
• /
• 2002

마이크로 연소실을 장착한 MAV 추진 장치용 단기통 MEMS 엔진을 제작하였다. 본연구에서는 MEMS 크기의 왕복운동 내연기관의 타당성을 검증하고 실용화를 위한 설계 및 가공데이터를 축적하고자 하였다. 엔진 블록은 가공의 정밀도와 내열성등을 고려하여 감광유리 웨이퍼를 사용하였으며, 점화 전극은 베이스 플레이트 위에 니켈 도금으로 제작하였다. 감광유리판은 등방성 에칭의 특성이 탁월하여 마이크로 엔진의 실린더와 피스톤과 같이 비교적 깊은 식각이 가능함을 확인하였다. 전체 엔진은 세 개의 별도 가공된 레이어를 접착하여 조립한다. 본연구의 엔진 연소실은 깊이는 1mn, 폭 2mn이며, 피스턴은 수소-공기 예 혼합 가스의 연소압력에 의하여 구동된다. 가공된 엔진의 연소실험을 통하여, 점화, 화염전파 및 피스턴 구동을 확인하였으며, 실용화를 위한 연구가 요구되고 있다.